A real period is the end result of a series of important ovarian and hormonal events including ovulation and the manufacture of progesterone. In contrast, a Pill bleed is withdrawal-bleed from synthetic steroids such as ethinylestradiol and drospirenone. Withdrawal bleeds happen when the synthetic steroids are stopped. That’s determined solely by the instructions of the drug manufacturer. They dose it to mimic a 28 day cycle, and that’s to reassure you you’ve had a period when you really haven’t.